How to check pushrod length on 5.9 magnum?

[ScampNYC]

Hi, I am building a 5.9 magnum for use in my 71 Scamp and need to check pushrod length, but am finding a lot of conflicting information on the web about how to do this.

I have a regrind camshaft in the motor now, which has been degreed. I plan on reusing the stock hydraulic roller lifters. My heads have been assembled by the machine shop and are sporting new Hughes valve springs. i do have an adjustable pushrod length checker tool.

I am reading on the web conflicting information on how to check pushrod length. A common issue seems to be that the valve springs will compress the hydraulic lifter and give you a false reading. Some are saying you need to use either a solid lifter or soft checking springs. Other say you can shim your lifter. Some say Hughes has an adjustable lifter used for checking pushrod length. Then others are saying you need to check by using the lifters and springs you plan on running.

I am at a point in my build where I am ready to bolt my heads on, and would love to figure this out as efficiently as possible.

Can anyone give me the straight dope on how to check pushrod length with my set up? Step by step instruction would be hugely helpful! Thanks in advance!

 

[RustyRatRod]

The light checking springs is the most "correct" way, especially using hydraulic lifters, as you don't want the plunger to be depressed.

 

[1994redram]

I used and old lifter. I took it apart and shimmed the plunger up with washers. I figured my push rod length with an adjustable push rod tool and added some length to it for lifter preload. It's been so long ago that I don't remember how much preload I put in them.

 

[ScampNYC]

The light checking is the most "correct" way, especially using hydraulic lifters, as you don't want the plunger to be depressed.

So to do it that way, I'd be:

1. Replacing intake and exhaust valve springs with checker spring on cylinder 1 with the head on the bench
2. Intall head with head gsket on the motor, fully torqued down
3. Perform check
4. Use compressed air to hold valve up while I put the hughes springs back on the head
   
   ... because in my mind it's not really ideal to take the head on and off and compress the head gasket twice.

Do I have this right?

 

[RustyRatRod]

So to do it that way, I'd be:

1. Replacing intake and exhaust valve springs with checker spring on cylinder 1 with the head on the bench
2. Intall head with head gsket on the motor, fully torqued down
3. Perform check
4. Use compressed air to hold valve up while I put the hughes springs back on the head
   
   ... because in my mind it's not really ideal to take the head on and off and compress the head gasket twice.

Do I have this right?

Who's to say what's "right"? But that's not "how I do it".

With checking springs, I would get my pushrod checker in, get that valve at half lift and adjust the pushrod checker so the rocker contact is right in the center of the valve tip. There's your correct length.

 

[RustyRatRod]

All this said, the FIRST thing you should do is contact Mike @ B3 racing engines and let him explain to you how to measure to make SURE your rocker shafts don't need relocating, because they probably do. He can walk you through how to do that and provide you with the correct relocating shims to get that done. THEN you can find your correct pushrod length.

 

[ScampNYC]

Who's to say what's "right"? But that's not "how I do it".

With checking springs, I would get my pushrod checker in, get that valve at half lift and adjust the pushrod checker so the rocker contact is right in the center of the valve tip. There's your correct length.

Then how would you change the springs back to the Hughes springs? Take the head off?

 

[RustyRatRod]

Then how would you change the springs back to the Hughes springs? Take the head off?

On the head spring compressor. I'd never remove the head if it was already on.

 

[ScampNYC]

Like one of thees guys?

 

[Professor Fate]

Unless you're using aftermarket valve gear, Magnums are non-adjustable so you have to get this right (they aren't Chevies- factory Magnums are designed to have the rockers tightened down).
Get the lifter you're checking on the base circle of the cam. Insert your pushrod checker, and adjust it until you have zero clearance, and can just feel light drag when trying to spin the checker by hand. This is your basic length. Whoever reground your cam should have supplied you with their recommended preload, add this number to your base length. Write it down, noting the position- ie #1 Ex., #2 Int., etc. Then move on to the next one, get it on the base circle and repeat. Check them all if you like, but at least check the 4 corner cylinders.
If you checked them using a used head gasket (of the type you will be using upon assembly), your numbers are good to go. If you checked without head gaskets, then add the gasket manufacturer's compressed thickness spec to your number.
With hydraulics you can either use the longest number, an average of your four longest numbers, etc. Everybody seems to have their own preference. This will be the length to order.
As far as using a "checking" lifter, you can gut one and fill it with washers, but it's difficult to get a washer stack at the right height. You can use a combination of washers and tightly pack a wad of tin foil in there to make it easier. In all honesty, you should just be able to use the lifter as-is, since you will NOT be compressing the plunger and the lifter's internal spring should be sufficient to hold the plunger stationary for checking purposes. If the plunger is dropping, you have lifter issues.
Likewise for a "checking spring", you should not need to use a lighter one since you are checking on the base circle of the cam and should NOT be compressing the spring at all- you are only going for a zero clearance number to which you add your preload.

 

[MOPAROFFICIAL]

Hi, I am building a 5.9 magnum for use in my 71 Scamp and need to check pushrod length, but am finding a lot of conflicting information on the web about how to do this.

I have a regrind camshaft in the motor now, which has been degreed. I plan on reusing the stock hydraulic roller lifters. My heads have been assembled by the machine shop and are sporting new Hughes valve springs. i do have an adjustable pushrod length checker tool.

I am reading on the web conflicting information on how to check pushrod length. A common issue seems to be that the valve springs will compress the hydraulic lifter and give you a false reading. Some are saying you need to use either a solid lifter or soft checking springs. Other say you can shim your lifter. Some say Hughes has an adjustable lifter used for checking pushrod length. Then others are saying you need to check by using the lifters and springs you plan on running.

I am at a point in my build where I am ready to bolt my heads on, and would love to figure this out as efficiently as possible.

Can anyone give me the straight dope on how to check pushrod length with my set up? Step by step instruction would be hugely helpful! Thanks in advance!

Before you put the intake on, find a load that is on the very back side, closed, then you will measure by taking an adjustable push rod or an old one that has an inch cut out of the middle and some all thread and two nuts between both ends. You will Zero Lash the push rod by watching the plunger cup and feeling for when it gets snug as you tighten the two nuts extending the push rod. Once you get to zero lash you will adjust it for an additional .035 depression of the lifter cup. Now on a Factory Magnum v8, Mopar would call for as much as .090 lifter preload... but that is with very weak Springs '200lbs' and a very low valve lift.

That is not the case with your new setup.


Best of luck.

 

[RustyRatRod]

Like one of thees guys?
View attachment 1716524409

I have a couple, but I don't particularly like them. I end up having to use a heave duty hose clap around the jaws so they don't slip off. Slows the process down a lot. I have a Lisle 16750 that I use if I have to remove springs on the head. I generally don't because I get "all that" right upon assembly.

 

[ScampNYC]

Unless you're using aftermarket valve gear, Magnums are non-adjustable so you have to get this right (they aren't Chevies- factory Magnums are designed to have the rockers tightened down).
Get the lifter you're checking on the base circle of the cam. Insert your pushrod checker, and adjust it until you have zero clearance, and can just feel light drag when trying to spin the checker by hand. This is your basic length. Whoever reground your cam should have supplied you with their recommended preload, add this number to your base length. Write it down, noting the position- ie #1 Ex., #2 Int., etc. Then move on to the next one, get it on the base circle and repeat. Check them all if you like, but at least check the 4 corner cylinders.
If you checked them using a used head gasket (of the type you will be using upon assembly), your numbers are good to go. If you checked without head gaskets, then add the gasket manufacturer's compressed thickness spec to your number.
With hydraulics you can either use the longest number, an average of your four longest numbers, etc. Everybody seems to have their own preference. This will be the length to order.
As far as using a "checking" lifter, you can gut one and fill it with washers, but it's difficult to get a washer stack at the right height. You can use a combination of washers and tightly pack a wad of tin foil in there to make it easier. In all honesty, you should just be able to use the lifter as-is, since you will NOT be compressing the plunger and the lifter's internal spring should be sufficient to hold the plunger stationary for checking purposes. If the plunger is dropping, you have lifter issues.
Likewise for a "checking spring", you should not need to use a lighter one since you are checking on the base circle of the cam and should NOT be compressing the spring at all- you are only going for a zero clearance number to which you add your preload.

This sounds great to me...

What about the whole checking the pattern on the rocker arm on the tip of the valve thing? You know, with the magic marker? Do I need to do that , or not really?

 

[Professor Fate]

This sounds great to me...

What about the whole checking the pattern on the rocker arm on the tip of the valve thing? You know, with the magic marker? Do I need to do that , or not really?

If running stock rocker gear, then what you have is what you have AFAIK. There are guide plates for aftermarket rockers and pushrods, but you can't relocate anything on a Magnum since the rockers are all stud-mount and not shaft-mount like an LA. Chevies used to have a weird offset cup/ball shim, but I haven't seen those in a long time and don't know if they ever came in Magnum sizes.

 

[ScampNYC]

Unless you're using aftermarket valve gear, Magnums are non-adjustable so you have to get this right (they aren't Chevies- factory Magnums are designed to have the rockers tightened down).
Get the lifter you're checking on the base circle of the cam. Insert your pushrod checker, and adjust it until you have zero clearance, and can just feel light drag when trying to spin the checker by hand. This is your basic length. Whoever reground your cam should have supplied you with their recommended preload, add this number to your base length. Write it down, noting the position- ie #1 Ex., #2 Int., etc. Then move on to the next one, get it on the base circle and repeat. Check them all if you like, but at least check the 4 corner cylinders.
If you checked them using a used head gasket (of the type you will be using upon assembly), your numbers are good to go. If you checked without head gaskets, then add the gasket manufacturer's compressed thickness spec to your number.
With hydraulics you can either use the longest number, an average of your four longest numbers, etc. Everybody seems to have their own preference. This will be the length to order.
As far as using a "checking" lifter, you can gut one and fill it with washers, but it's difficult to get a washer stack at the right height. You can use a combination of washers and tightly pack a wad of tin foil in there to make it easier. In all honesty, you should just be able to use the lifter as-is, since you will NOT be compressing the plunger and the lifter's internal spring should be sufficient to hold the plunger stationary for checking purposes. If the plunger is dropping, you have lifter issues.
Likewise for a "checking spring", you should not need to use a lighter one since you are checking on the base circle of the cam and should NOT be compressing the spring at all- you are only going for a zero clearance number to which you add your preload.

Do I need to prime the oil pump first, or no?

 

[Professor Fate]

Do I need to prime the oil pump first, or no?

To check pushrod length? No.
You can submerge the lifters in oil overnight first (to fill them) if it makes you feel more comfortable, but not really necessary in this instance.
Just don't smear the cam up with cam paste or anythig like that as it can affect your readings (you don't need it with roller lifters anyway, but I'm just sayin').

 

[RustyRatRod]

Yeah, I had LA on the brain instead of Magnum. Sorry.

 

[Illahe]

This sounds great to me...

What about the whole checking the pattern on the rocker arm on the tip of the valve thing? You know, with the magic marker? Do I need to do that , or not really?

Rusty has a good point.

If you are running aftermarket rockers (Cheby) with the stud, you can get the pushrod length gauge and check the length with it. I believe amazon has them.

I set up some 318B E.Q. heads this way with a SFT cam and the valve train was stable. My set up ran guide plates and stamped roller tip Elgin (IIRC) Rockers. They were about 110 bucks.

If your running hydraulic lifters you'll want the lifter plunger mid travel (IIRC) I believe.

IMM has the pushrod lengths in an article as well. IMMENGINES.COM Call Brain he's a member.

 

[Bodyperson]

I agree with most of this, especially how that tool sucks. It's a hand killer. No reason to pull a spring. You can easily feel the drag when you bring the adjustable push rod up to lenght by having every thing lightly oiled and spinning the adjustable pushrod until you feel a slight drag. The main thing is making sure you are on the base circle of the camshaft. I turn the engine over until I see the the exhaust lifter and intake lifter cycle (turning the crankshaft clockwise) and then go a little further in crank rotation. That puts both the exhaust and intake lifters on both of their base circles. You can then install the adjustable pushrod and bring it up for measurements. You then remove the rockers and pull the pushrods and measure them and as has been been mentioned, add for lifter preload. It would be nice to have 2 adjustable pushrods to check both exhaust and intake at the same time but there should be no difference. Make sure everything is engaged correctly. With mopars radical lifter angle it is easy to get out of wack.

 

[Kern Dog]

The light checking springs is the most "correct" way, especially using hydraulic lifters, as you don't want the plunger to be depressed.

I don't see why. You're trying to establish a zero lash point to get the number. Why would you want checking springs ? I too have seen videos where dudes have used them. They are great for checking piston to valve clearance.

Get the lifter you're checking on the base circle of the cam. Insert your pushrod checker, and adjust it until you have zero clearance, and can just feel light drag when trying to spin the checker by hand. This is your basic length.

This makes sense.

For a "checking spring", you should not need to use a lighter one since you are checking on the base circle of the cam and should NOT be compressing the spring at all- you are only going for a zero clearance number to which you add your preload.

Same there. More sense.

No reason to pull a spring. You can easily feel the drag when you bring the adjustable push rod up to length by having every thing lightly oiled and spinning the adjustable pushrod until you feel a slight drag. The main thing is making sure you are on the base circle of the camshaft. I turn the engine over until I see the the exhaust lifter and intake lifter cycle (turning the crankshaft clockwise) and then go a little further in crank rotation. That puts both the exhaust and intake lifters on both of their base circles. You can then install the adjustable pushrod and bring it up for measurements. You then remove the rockers and pull the pushrods and measure them and as has been been mentioned, add for lifter preload. It would be nice to have 2 adjustable pushrods to check both exhaust and intake at the same time but there should be no difference. Make sure everything is engaged correctly. With mopars radical lifter angle it is easy to get out of wack.

Dwayne Porter stated that he adjusts the pushrod tool until it has no vertical slack and where the rocker arm just gets to the point where it doesn't move either.
From what I'm told, the Magnum series engines had a huge amount of preload when they were new, something like .080.

 

[Bodyperson]

I don't see why. You're trying to establish a zero lash point to get the number. Why would you want checking springs ? I too have seen videos where dudes have used them. They are great for checking piston to valve clearance.



This makes sense.



Same there. More sense.



Dwayne Porter stated that he adjusts the pushrod tool until it has no vertical slack and where the rocker arm just gets to the point where it doesn't move either.
From what I'm told, the Magnum series engines had a huge amount of preload when they were new, something like .080.

I have not built a magnum. I'm just going off what I understand. Id be willing to go A little looser on a new engine.

 

[RustyRatRod]

I don't see why. You're trying to establish a zero lash point to get the number. Why would you want checking springs ? I too have seen videos where dudes have used them. They are great for checking piston to valve clearance.



This makes sense.



Same there. More sense.



Dwayne Porter stated that he adjusts the pushrod tool until it has no vertical slack and where the rocker arm just gets to the point where it doesn't move either.
From what I'm told, the Magnum series engines had a huge amount of preload when they were new, something like .080.

I explained myself pretty good. So that you can get the valves at half lift and then adjust the pushrod tool to center the rocker tip on the valve tip. The pushrod is correct at that length. That's all that really needs to be done. Do it however you want.

 

[Kern Dog]

I wasn't painting you as a liar or wrong.
I imagine that in a totally new build, you'd want to check everything.
I was measuring for pushrods today for the roller camshaft swap I'm doing in my 440/495. I've had these same rocker arms on these same heads for 13 years. I've had no irregular valve stem wear so for me, reading about "half lift, adjust pushrod tool to center the rocker tip" seemed unusual.
I'm willing to change my view on things if a compelling rebuttal is made. Nobody knows everything.

 

[Bodyperson]

I explained myself pretty good. So that you can get the valves at half lift and then adjust the pushrod tool to center the rocker tip on the valve tip. The pushrod is correct at that length. That's all that really needs to be done. Do it however you want.

I wasn't painting you as a liar or wrong.
I imagine that in a totally new build, you'd want to check everything.
I was measuring for pushrods today for the roller camshaft swap I'm doing in my 440/495. I've had these same rocker arms on these same heads for 13 years. I've had no irregular valve stem wear so for me, reading about "half lift, adjust pushrod tool to center the rocker tip" seemed unusual.
I'm willing to change my view on things if a compelling rebuttal is made. Nobody knows everything.

It seams like RRR is working on a Chebby. Magnums are not adjustable. The chevy enginge can change the geometry with pushrod length with it's adjustable studs. Maybe thats available for Chrysler. I think it was mentioned.

 

[RustyRatRod]

It seams like RRR is working on a Chebby. Magnums are not adjustable. The chevy enginge can change the geometry with pushrod length with it's adjustable studs. Maybe thats available for Chrysler. I think it was mentioned.

No, I'm ASSUMING (probably dangerous) that if the OP is building anything of a performance engine, that he will be using an adjustable rocker arm. That's the only way I'd go on anything above stock to get the lifter preload dead on. In order to get it that close with a non adjustable valve train, you'd probably need 16 different length pushrods. Any performance engine needs to be able to dial preload in spot on. Heck, it even makes a stock engine work better, because it gets the geometry correct. Yall build however you want. I don't care. He asked for advice. I gave it.